Motor control.



' PATENTED MAY 14, 1907. W. L. MERRILL;

MOTOR CONTROL. APPLICATION FILED 0OT.15, 1906.

Wjtnesses:

Inventor:

Wilbur L. errill,

umrnnfsmrns AT N OFFICE WILTBZUR, 1.. MERRILL, OF SCHENECTADY, NEW YORK, AssIeNoR To GEN-'7 J-RAL ELECTRIC COMPANY, A CORPORATION or NEW YORK.

moron com-nor.

Specification of Letters Patent.

Patented may 14, 1907- To all whom it nun concern:

Be. it known that I, WILBUR L. MERRILL,

a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and -useful Improvements in Motor Control, of

which the following is a speciiication.

My invention relates to the control of electric motors for driving loads over wide [0 ranges of speed. For certain kinds of motor-drives, in which wide ranges of speed are required, such as in the operationofgun. turrets and printing presses, it has been proposed heretofore to emplo two motors, the smaller of'which is geare to the load through speed-reducing gearing so as to start and drive it at low speed, while the larger motor is cared so as todrive the load at high speed. he smaller motor is'ordinarily provided with a clutch so that it can be disconnected from the load when the larger motor is operating. The 'method of speed control that has usually been employed heretofore for such a comb- 2 5 nation is the resistance method, but in cases where a constant speed is desired for any] given position of the controlli switch wit I varying load, resistance "contro is not suit able, since the voltage drop in the resistance ;o varies with varying load on the motor. I In such cases a voltage control is referable,

- but since the smaller motor mustlle cut out at its highest speed, and the larger motor simultaneousl cut in at its lowest speed, the

g5 usual method of volt e control make a quick and smooth transition fromone motor to the other difiicult to obtain.

. M invention broadly. consists in employing or the purpose of this control separate .0 sources of variable voltage for the two motors, and therefore I, am enabled to make a quick and smooth transfer from the smaller motor at maximum voltage to the' larger motor at minimum voltage; g 5 More specifically stated, employ two generators of different capacities, corres onding to the two motors, which may be iven from a constant potential source ofsugply by a constant-speed motor, and provi e a 0 switch for connecting the enerators to the two motors respectively an for v voltages delivered by the generators. At starting the smaller generator is" connected creased, further to increase the voltage to the smaller motor. The field of the smaller generator is then gradually increased to maximum value. t this point the larger generator isconnected with a weak field to the larger motor. The gea between the two generators and the load is arranged to give a load-speed with the smallermotor operating at maximum voltage approximately the motor operating at minimum voltage. 'ter the larger motor has beenoonnected to its generator, the smaller motor is mechanically 'sconnected from the load and the voltage of the larger generator is t en ad-speed. My invention will best be understood by with a weak field and consequently lowsame as with the largr gradually inreference to the accompanying drawing, which shows diagrammatically a control system arranged in accordance with my 1nvention. 5

In the drawing, A represents a shaft which is geared or otherwise connected to the load which is to be driven. B-represents the armature of. the lar or motor, which is connected directly to t e shaft A. b represents the field of this motor.

0 represents the armature of the smaller motor, through the low-spped gearing formed by the piniondand gear c represents the motor-field.

- E 'isa magnetic clutch for connecting and disconnecting the shaft A and the gear D. F represents supply-conductors connected to a constant potential source. a

G is a shunt-wound motor connected to and supplied by the constant potential c'onductors H and I represent the armatures of a large and a small generator, which the motor G, the capacities of which'co'rrespond respectively to the capacities of. the motors B and C. h and'irepresent the shuntfields of the two generators, which may also be provided with series fields h and 'i, if desired, in order to maintain-the voltage approximately constant under varying load with a given strength of shunt field.

J and j represent two field-resistances which are connected in series with the fields h and '8, respectively.

represents a controlling switch.

which is connected to the shaft A" are driven by As the controller K is moved throug other positions the resistance j is short-cir- 'cuited step-by-step, until finally it is all cut out of circuit. h

e smaller generator is then delivering its maximum voltage-to the smaller motor. At this point'the circuit of the larger motor is closed. The circuit of the 'field It has already been closed with all of resistance J in series. Consequently, the generator-armature H supplies its minimum voltage to the larger motor. 'At the same timethe circuit of the magnetic clutch E is broken. The gearing between the two motors and the load is so arranged that the same load-speed is obtained with the larger I'notor operating at minimum voltage as with the smaller motor operating at maximum voltage; Consequently, an even transition "cuts out sections of resistance J, increasing the, voltage deliveredto the large motor, so

from. one motor to the other is obtained. Further movement of the controlling switch asfurther to increase-the speed of the shaft A. The small m'otor" may continue to run idle at full speed, so as to be ready to take up the load on the return movement of the controlling switch K. I do. not desire to parts here shown, but aim in the a pended claims to cover all modifications w ich are within the scope of my invention.

-What I claim as new and'desire to secure by Letters Patent of the United States, is,

5 volta e for eachinotor.

fn combination with a load to be driven,. two electric motors -0f difierent capacities, low-s eed gearing be ween the smaller motor tor, said gear 1. In combination with a load to be driven,

two electric motors of different ca acities, mechanical connections between t e load and both motors whereby the load may be driven by either motor but'j at different speeds, and .a separate source-of variable and tr e load, high-speed gearing between the larger motor and the toad, and a separatev source of variable voltage for each motor.

3-. in cei'iihinai In i to d two 'ele ioiv speeil M15. 'Cii l(,

n the semi H i; i gearing is. u tneica-d, and a-sepaunable voltage for each inc-- .g ieing arranged to g ve apthe same load-speed with the proximateiy its limit myself to the par- -ticular construction and arrangement of larger motor operating at its minimum voltage and with the smaller motor operating at its maximum voltage.

low-s ed gearin between the smaller motor and t e load, hig -speed gearing between the larger motor, and the load, a separate source of variable voltage for each motor, and a single switch controlling the voltage supplied to othmotors. I

5. In combination with a load to be driven,

low-s eed gearin between the smaller'motor and t e load, hig -speed gearing between the larger motor andthe load, a separate source trolling switch arranged to control thevoltage su lied to each motor and to transfer the load f rom the smaller motor'operating at maximum voltage to the larger motor operating at minimum voltage, the gearing being arranged to give approximately the same load-speed before and after the transfer.

6. In combination with a load to be driven, two electric motors of (liflerent capaciti'cs, low-s eed gearin between the smaller motor and t e load, hig -speed gearing between the larger motor and the load, a separate source of variable voltage for each motor, and means for o crating said motors alternately to drive the oad.

7. In combination with a load to be driven, two electric motors of different capacities, low-s eed gearing between the smaller motor and t e load, high-speed gearing between the largermotor and the load, a separate source of variable voltage for each motor, and means for alternately breaking the circuit of the larger motor and mechanically disconnecting the smaller motor from the load.

8., In combination with a load to be driven, two electric motors of different capacities,

and t e load, hig -s eed gearing between the larger motor and tlie load, and a'separate source of. variable voltage for each motor, a magnetic clutch in the gearing between the the larger motor and of the clutch.

two electric motors of different capacities, mechanicai connections between the lea-1i and both motors, whereby the load 255e, dr ven by her motor but d2: z--I l s te" constant potential supply, circuit,

- ns for deriving from said circuit two speetive motors.

10. In combination with a load to be driven, two electric motors of different ca.-

ing between the larger motor and the load, a

low-speed gearin between the smaller motor smaller motor and the load, and a controlling" switch for alternately breaking the circuit of;

9. In combination with a load to be driven,

i: ependent variable voltages for the re-; 5 r25" 4.'Incombination withaload to be driven, two electric motors of different capacities,

two electric motors of different capacities, f

of variable voltage for each motor, and a conpacities, low-speed gearing between the' smaller motor and the load, high-speed gear- We it n i constant potential supply circuit, and means I voltage.

for deriving from said circuit two independent variable voltages for the respective motors.- i

11. In combination with a load to be driven, two electric motors of different. ca

,pacities, low-speed gearing between the:

smaller motor and the load, high-speed gearing between the larger'motor and the load, a constant potential supply circuit, and means for deriving from said circuit two independent variable voltages for the respective motors,-the gearing between the load and the motors being arranged to give approximately thesame load-speed with the larger motor 0 'erating at its minimum voltage and with t e smaller motor operating at its maximum '12. Incombination with a load to be driven, two electric motors of different capacities, low-speed gearing between the smaller motor and the load, high-speed gearing between the 'largermotor andthe load, a constant otential supply circuit, means for deriving from said circuit two independent variable voltages for the respective motors,

and a sin le switch controlling the voltage supply to 0th motors.

13. In combination with "a load to be driven, two electricmotors of different capacities, low-speed gearing between the smaller motor and the load, high-speed gearing between the larger motor and the load, a constant otential supply circuit, means for deriving om said circuit two independent variable voltages for the respective'motors, and means for operating said motors alternately to drive the load.

1 14. In combination with a. load to be' driven, two electric motors of different ca pacities, mechanical connections between the load and both motors, whereby the load may be driven by either motor but vat different speeds, a constant potential supply circuit, an electric motor connected thereto, two generators of different capacities driven thereby,

means for connecting the two generators to the two load-driving motors respectively, and means for controlling the voltage delivered by each of said generators.

' different capacities driven by said motor, and

a switch arranged to connect the two generators to the'two motors'respectively and to load, said 15. In combination with a load .to be hand this 13th vary the voltage delivered by said generators, said gearing between the load and the motors being arranged to give approximately the same load-speed with the larger motor operating at minimum voltage and with the smaller motor operating at maximum voltage.

16. In combination with a load to be driven, two electric motors of different ca pacities, low-speed gearing. between the smaller motor and the load, high-speed gearing between the larger motor and the load, a

constant potential supply circuit, an electric motor connected thereto, two generators of different capacities driven by said motor, a switch arranged to connect the two generators to the two load-drivingmotors respectively and successively and to vary the voltage delivered by said generators, and means formechanically disconnecting the smaller motor from the loadwhen the larger motor is electrically connected to its generator.

17. In combination. with a load to be driven, two electric motors of different ca pacities, mechanical connections between the load .andboth motors, whereby the-load may be driven by either motor but at difierent speeds, a constant potential supply circuit, an electric motor connected thereto, two generators of different capacities driven thereby for supplying the, two load-driving ranged to operate said motors alternately for drivin the load.

18. n combination with a load to be driven, two electric motorsof different ca "pacities, low-speed gearing between the smaller motor and the load, high-speed gearing between the larger motor and the load, a

constant potential'supply circuit, an electric motor connected thereto, two generators of difierent capacities driven by said motor for supplying the two load-driving motors respectively, means for controlling the voltage delivered by said generators, and controlling; means for the two motors arranged to operate said motorsalternately for driving the gearing being arranged to give a proximate smaller motor operating at maximum voltage and with the larger motor operating at minimum voltage.

In witness whereof, I have hereunto set my day of October, 1906.

WILBUR L. MERRILL, Witnesses: c

BENJAMIN B. HULL, HELEN ORFoRD.

y the same load-speed with t e 

